WO2005001539A1

WO2005001539A1 - Camera lens-positioning device using shape memory alloy and camera using the device

Info

Publication number: WO2005001539A1
Application number: PCT/JP2003/008220
Authority: WO
Inventors: Makoto Ito; Masaaki Inaba
Original assignee: Nokia Corporation
Priority date: 2003-06-27
Filing date: 2003-06-27
Publication date: 2005-01-06
Also published as: JP2009258760A; JPWO2005001540A1; US7177539B2; EP1640757A1; KR20060028648A; CN100359355C; AU2003244145A1; EP1640757A4; US20060098968A1; CN1813212A; KR100821697B1; WO2005001540A1

Abstract

A positioning device for a camera lens. The device comprises a housing; a lens support member for supporting a camera lens, provided in the housing so as to be movable in a direction approaching a shooting object or in a direction moving away from the shooting object; a guide member for guiding the lens support member in its movement direction, provided along a movement direction of the lens support member; a member for always applying force to the lens support member either in a direction approaching a shooting object or in a direction moving away from the shooting object; and shape memory alloy for appropriately applying force to the lens support member in the opposite direction to the member for always applying force. A movement range in movement directions of the lens support member can be limited by the engagement of the lens support member and the housing. With the device, positioning with required accuracy of a camera lens can be provided with low cost, low power consumption, simple structure, and small space.

Description

Description Positioning device for camera lens using shape memory alloy and

Camera using this positioning device

The present invention relates to a camera lens positioning device for executing a variable focus mechanism of a camera such as an autofocus mechanism, an auto macro mechanism, an electric macro mechanism, a zoom mechanism, and more specifically, a camera lens using a shape memory alloy. The present invention relates to a positioning device and a camera using the positioning device. Background art

To take better photos, it is necessary to consider not only the focus position but also the depth of field. The factors that determine the depth of field include the resolution and the maximum permissible circle of confusion. In general, as the resolution increases for imaging devices of the same size, the maximum permissible distant view decreases, resulting in a narrower depth of field. Therefore, especially when the resolution is increased, it is necessary to determine the center of the depth of field to an appropriate position. The center of this depth of field can be determined by the position of the camera lens, as well as the focus position. Therefore, for example, in order to more closely photograph an object to be photographed or an object to be photographed farther away, it is necessary to position the camera lens as accurately as possible. Particularly, in recent years, a mobile phone with a high resolution has been desired, so that even in a small camera used for a small device such as a mobile phone, the positioning of the camera lens can be performed with higher accuracy, lower cost, and lower cost. There is a need for power, a simple structure, and a configuration that can be implemented in a small space.

By the way, some conventional small cameras used for mobile phones have a camera lens Some have provided a feature called "macro" mode to make the decision. This “macro” mode function is used when shooting a closer object. However, manual operation is required to execute the “macro” mode. Obviously, this operation is complicated. On the other hand, an autofocus function that does not require manual operation has also been realized. However, in this case, a device such as a DC motor (DCM) or a stepping motor (STM) is required as an actuator for moving the lens. Some DCMs and STMs are larger than 4 mm in diameter and require a significant amount of space to install them. Therefore, when these DCM and STM are used, it is difficult to reduce the size of the device, and they are not suitable for a small device such as a mobile phone. Also, DCM requires gears and sensors to move the lens, while STM requires driving devices, electrical circuits and sensors such as lead screws and gears to move the lens. Therefore, it has disadvantages such as high power consumption due to mechanical drive, complicated structure, many failures, and high cost.

In the past, shape memory alloys were sometimes used to move camera lenses and the like. For example, Japanese Patent Application Laid-Open No. 2000-137715 discloses that two plate-shaped shape memory alloys are deformed in response to a change in temperature so that a space between these plate-shaped shape memory alloys is formed. An apparatus for moving the position of a camera lens through contact between a part of the arranged camera lens and a shape memory alloy is disclosed. However, this device is only a device for moving the position of the camera lens according to a temperature change, and does not relate to a technique for freely positioning the position of the camera lens. In Japanese Patent Application Laid-Open No. Hei 6-230457, two thin line-shaped shape memory alloys are provided on each of the left and right sides of the diaphragm member of the force ram, and by utilizing the function of these shape memory alloys, An aperture adjusting device that moves an aperture member according to a temperature change is disclosed. This device is a device that moves the diaphragm member according to the temperature change. It does not relate to a technique for positioning freely. Disclosure of the invention

The present invention provides a positioning device capable of moving a camera lens using a shape memory alloy to determine a position with required accuracy, and a camera using the positioning device with low cost, low power, a simple structure, and a small space. Is what you do.

According to the present invention, a housing, a lens support member that supports a camera lens, and is provided on the nozzle so as to be movable in a direction approaching or away from the imaging target, and a lens support member A guide member provided along the movement direction for guiding the lens support member in the movement direction; and the lens in a direction of approaching the object to be photographed or away from the object to be photographed. A member that constantly applies a force to the support member, and a shape memory alloy that appropriately applies a force to the lens support member in a direction opposite to the member that constantly applies the force, wherein the lens support member and the housing are engaged. Thereby, a camera lens positioning device that regulates a movement range of the lens support member in the movement direction is provided. In the above device, the shape memory alloy may be such that it shrinks when an electric current is applied. In the above device, the member that constantly applies the force may be a coil panel.

Further, in the above apparatus, a projection or a hole is provided in the lens support member, and a hole or a projection is provided in the nosing corresponding thereto, and the projection is inserted into the hole, and the moving direction is changed. The movement range of the lens support member may be restricted by causing the wall of the hole disposed opposite to the projection to collide with the projection. Further, according to the present invention, there is provided a camera provided with the above positioning device. Brief Description of Drawings

FIG. 1 is a schematic perspective view of the inside of a camera module according to the present invention as viewed from the inside.

FIG. 2 is a partial perspective view of a housing of the camera module of FIG. BEST MODE FOR CARRYING OUT THE INVENTION

A camera module according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic perspective view of the inside of the camera module as viewed from the inside, and FIG. 2 is a view of a portion # 1 of the housing of the camera module. Note that the camera module 1 shown in these figures only constitutes a part of the camera and is not used alone. Moreover, since the state when this camera module Λ ^ み is inserted into the camera is clear, it is not particularly shown.

The camera module 1 mainly includes a housing 11, a movable lens barrel 13 movably attached to the housing 11, a guide shaft 15 for regulating a moving direction of the lens barrel 13, A coil spring 17 that applies a normal force to the lens barrel 13 in one predetermined direction, a shape memory alloy 16 that drives the lens barrel 13 by appropriately applying a force in a direction opposite to the one predetermined direction, and photographing It consists of a photo sensor 18 for confirming the position of the object.

The lens barrel 13 is formed in a substantially cylindrical shape as a whole. The camera lens 19 is fixedly provided near the center hole of the lens barrel 13. In particular, the front part of the lens barrel 13 is inserted into a through hole 22 provided in the front plate 21 of the housing 11. As a result, the front annular portion (not shown) of the camera lens 19 and the lens barrel 13 is exposed on the front surface of the housing 11 (the front side of the front plate 21 of the housing 11). The lens barrel 13 can be moved in the direction of retracting into the housing 11 or protruding from the housing 11 while being inserted into the through hole 22. The As described above, the camera lens 19 moves in accordance with the movement of the lens barrel 13 due to the force fixed to the lens barrel 13. By this movement, the position of the camera lens 19 is adjusted, and the focus of the camera is adjusted and the zoom is performed.

On each of the left and right side surfaces on the rear side of the lens barrel 13, there are provided substantially semicircular protrusions 24 A and 24 B protruding from the left and right sides, respectively. A through hole 26 is provided near the center. The guide shafts 15 pass through these through holes 26 respectively. Thereby, the lens barrel 13 can be guided along these guide shafts 15. For example, the lens barrel 13 extends vertically from the back of the front plate 21 of the housing 11 toward the inside of the housing 11 so that the lens barrel 13 can move vertically with respect to the front of the housing 11. A guide shaft 15 may be provided on the machine. In FIG. 1, in particular, a part of the left substantially semicircular projection 24A is shown in a broken state so that the relationship between the guide shaft 15 and the substantially semicircular projection 24 is clear.

Further, a vertical protruding portion 29 having a rectangular cross section protruding upward is provided on an upper side surface near the middle of the lens barrel 13. The upper part of the vertical protrusion 29 is inserted into a rectangular hole 28 provided in the upper plate 23 of the housing 11 when the power module is assembled. In particular, the length of the vertical protrusion 29 in the direction of movement of the lens barrel 13 is such that the length of the hole 28 in the housing 11 in the above direction is such that the lens barrel 13 can move inside the hole 28. It is slightly smaller than the length. A wall 3OA and a wall 30B are formed inside the hole 28 of the housing 11 along the moving direction of the lens barrel 13 so as to face each other. These walls 30 A, 30

By providing B, the movement range of the lens barrel 13 partially inserted into the hole 28 of the housing 11 can be regulated. The lens barrel 13 collides with these walls 30 A, 3 OB in the direction of its movement, so that its range of movement- Is limited. At this time, the length (distance) in which the lens barrel 13 can move is apparently (the length between the wall 3 OA and the wall 3 OB) one (particularly the tip of the vertical protrusion 29 in the moving direction). (Thickness in the vicinity). This may be considered to be, for example, about 0.05 mm. It should be noted that the walls 30A and 3OB can be integrally formed as a part of the housing 11 with a mold or the like. Thus, by providing the walls 30A and 3OB as a part of the housing 11, there is no need to separately provide a member for regulating the moving range of the lens barrel 13, and an adjusting mechanism for adjusting the moving range. It is not necessary to provide

The coil spring 17 is a member for applying a force in one predetermined direction on the lens barrel 13. The coil spring 17 is provided so as to surround the guide shaft 15. One end of the coil spring 17 collides with the front plate inner wall 27 of the housing 11, and the other end thereof has a substantially semicircular projection 2 4 of the lens barrel 13. Collides with the front of the 2 5. By the function of the coil spring 17, the lens barrel 13 is constantly pressed in the direction away from the object to be photographed (in the direction of arrow a in the drawing), in other words, in the direction in which it collides with the wall 3OA. For example, in the case of the SXGA camera, the focus point of the camera at this time is about 1 m, and the depth of field is about 70 cm to infinity.

The shape memory alloy 16 functions as an actuator that moves the lens barrel 13. The shape memory alloy 16 may be formed in a thread shape, for example. Its diameter is about 1 mm force or less. The shape memory alloy 16 is taken in from the outside of the housing 11 through a hole 32 provided in the front plate 21 of the housing 11, and the tip of the shape memory alloy 16 is a substantially semicircular projection 2 4 of the lens barrel 13. It is fixed to a rod 3 4 that extends vertically from the top of. The shape memory alloy 16 is formed so as to shrink when a current is applied, and to gradually return to the original length when the application of the current is stopped. It should be noted that the current is applied to the shape memory alloy 16 only at the time of photographing, and therefore no wasteful power is consumed by this shape memory alloy. Shape memory alloy 1 When the lens barrel 6 is retracted, the lens barrel 13 at the normal position is pushed by the force of the coil spring 17 through the contact between the shape memory alloy 16 and the rod 34 to approach the object to be photographed (arrow in the figure). Direction), in other words, a part of the vertical protrusion 29 of the lens barrel 13 is moved in a direction in which it collides with the wall 30B (a direction approaching the wall 30B). Conversely, when the shape memory alloy 16 returns to its original length, the lens barrel 13 moves away from the object to be photographed (in the direction indicated by the arrow a) while being promoted by the action of the coil spring 17, in other words, However, a part of the vertical projection of the lens barrel 13 is moved in a direction in which the lens barrel 13 collides with the wall 3 OA (a direction approaching the wall 3 OA). When the lens barrel 13 completely collides with the wall 30B, in the above SXGA camera example, the focus point is about 40 cm, and the depth of field is about 25 cm to 1 m. It is.

The extent to which the shape memory alloy 16 shrinks when a current is applied can be adjusted to some extent by the amount of current. However, it is difficult to adjust the amount of current, and in this case, the manufacturing cost also increases. Also, even if the same amount of current is applied, the size of shrinkage varies for each shape memory alloy. On the other hand, even when the same shape memory alloy is used, the size of shrinkage varies depending on room temperature and humidity. As described above, the shape memory alloy has a force having an unfavorable property. In the present invention, since the movement range of the lens barrel 13 is regulated by the wall 30A and the wall 30B, an inexpensive shape memory alloy is used. Thus, the positioning of the camera lens can be performed with the required accuracy, at a low cost, and with a simple structure. Since the shape memory alloy has unfavorable properties as described above, the shape memory alloy to be used is one having a sufficient driving amount to cover the moving range of the lens barrel 13, preferably a lens It is preferable that the barrel 13 has a drive amount slightly larger than the movable range in which the barrel 13 is to be moved.

The photo sensor 18 is used for confirming the position of the photographing target. The photo sensor 18 emits IR (infrared) light to the subject and detects whether the reflected light can be received by the light receiving sensor (ON state) or cannot be received (OFF state). To do. As a result, for example, if it is in the ON state, it is determined that the imaging target is at a relatively close position, whereas if it is in the OFF state, it is determined that the imaging target is at a relatively far position. This detection result of the photo sensor 18 can also be used for automatically adjusting the position of the lens barrel 13. For example, the detection result may be processed by software, and the magnitude of the current applied to the shape memory alloy 16 may be determined based on the processing result.

A part 36 of the lens barrel 13 extends to the photo sensor 18. This extended portion 36 of the lens barrel 13 is a portion for shielding the IR from the photosensor 17 from light. Furthermore, based on whether the IR of the photosensor 17 is blocked or unblocked by the extension 36, it is determined whether the camera lens 19 is securely moving or the desired position of the camera lens. This is a part to confirm that the position is correctly determined. For example, in a normal state, when the lens barrel 13 is at a position away from the object to be photographed (a position moved in the direction of arrow a in the drawing), the photo sensor 17 is not shaded, and When it is in the approaching position (the position moved in the direction of arrow a in the figure), the photo sensor 17 is shielded from light. However, if a camera lens does not move due to foreign matter entering the movable part of the lens barrel 13 or some other trouble, the light blocking state of the photo sensor 18 becomes abnormal. Abnormalities can be detected.

As is apparent, according to the configuration of the present invention, the camera lens can be positioned with high accuracy by using an inexpensive shape memory alloy. In addition, a camera module having such a function can be provided with low cost, low power, a simple structure, and a small space.

It should be noted that a leaf spring or another elastic member or other material may be used in place of the above coil spring. Further, in the above embodiment, the lens barrel is photographed by a coil spring. The lens barrel was moved in the direction away from the elephant, on the other hand, in the direction approaching the object to be photographed by the shape memory alloy. The lens barrel may be moved in a direction away from the object to be imaged.

Further, in the above embodiment, the housing is provided with a hole and the lens barrel is provided with a protruding portion. However, conversely, the lens barrel may be provided with a hole and the housing may be provided with a protruding portion. Further, it is sufficient that the housing and the lens barrel are engaged with each other so that the range of movement of the lens barrel is regulated by the housing. Here, it is sufficient if the range of movement of the lens barrel can be regulated by the housing.

Claims

The scope of the claims

1. In the camera lens positioning device,

No, aging,

A lens support member that supports the camera lens and is provided along the moving direction of the lens support member, the lens support member being provided on the housing so as to be movable in a direction approaching or moving away from the imaging target; A guide member for guiding the lens support member in the movement direction;

A member that constantly applies a force to the lens support member in a direction in which the lens support member approaches the imaging target or moves away from the imaging target;

A shape memory alloy that appropriately applies a force to the lens support member in the opposite direction to the member that constantly applies the force.

An apparatus, wherein a movement range of the lens support member in the moving direction is regulated by engaging the lens supporting member with the nodging.

2. The device according to claim 1, wherein the shape memory alloy shrinks when an electric current is applied.

3. The device according to claim 1, wherein the member that constantly applies a force is a coil spring.

4. The device according to any one of claims 1 to 3, wherein a protrusion or a hole is provided in the lens support member, and a hole or a protrusion is provided in the housing correspondingly. The lens support member is inserted into the hole, and the moving range of the lens support member is adjusted by colliding the wall of the hole, which is disposed facing the moving direction, with the protrusion. Device to regulate.

5. A force lens provided with the positioning device according to any one of claims 1 to 4.